Acetic Anhydride → Ethyl 3-acetyl-4,5-dimethyl-1H-pyrrole-2-carboxylate

HRID 917795Notes

Reaction equation

HRID 917795 reaction equation
[Cl-].[Al+3].[Cl-].[Cl-].[C:5](OC(=O)C)(=[O:7])[CH3:6].[CH2:12]([O:14][C:15]([C:17]1[NH:18][C:19]([CH3:23])=[C:20]([CH3:22])[CH:21]=1)=[O:16])[CH3:13]>ClC(Cl)C>[CH2:12]([O:14][C:15]([C:17]1[NH:18][C:19]([CH3:23])=[C:20]([CH3:22])[C:21]=1[C:5](=[O:7])[CH3:6])=[O:16])[CH3:13]

Participants

5

Reactant 3

HCID 7918Acetic AnhydrideHCID 137478Ethyl 4,5-dimethyl-1H-pyrrole-2-carboxylateHCID 6451240Aluminum(III) Chloride

Product 1

HCID 12288399Ethyl 3-acetyl-4,5-dimethyl-1H-pyrrole-2-carboxylateYield 60%

Reagents, catalysts & solvents 1

HCID 63651,1-DichloroethaneSolvent2×

Procedure

To a solution of aluminum chloride (50.19 g, 0.376 mol) in dry dichloroethane (580 mL) at 25° C. was added slowly acetic anhydride (17.75 mL, 0.188 mol). The resulting mixture was stirred at room temp. for 10 minutes, then a solution of pyrrole 8b (10.49 g, 0.0627 mol) in dichloroethane (30 mL) was added and the reaction mixture was stirred at room temp. for 2 h. After an additional 3 h at 80° C., the mixture was poured into ice water and extracted with dichloromethane. The organic layer was dried with anhy. sodium sulfate and concentrated in vacuo to an orange residue. Short plug filtration over silica gel (30% ethyl acetate/70% hexanes) gave 7.5 g (60%) of ethyl-3-acetyl-4,5-dimethyl-2-pyrrole carboxylate 9b.

Workup

  1. stirringthe reaction mixture was stirred at room temp. for 2 h
  2. waitAfter an additional 3 h at 80° C.
  3. extractionextracted with dichloromethane
  4. customThe organic layer was dried with anhy
  5. concentrationsodium sulfate and concentrated in vacuo to an orange residue
  6. filtrationShort plug filtration over silica gel (30% ethyl acetate/70% hexanes)

Sources & evidence

ORD record
ord-172f92a971794283a861c1c82b68f434
Source dataset
uspto-grants-2007_09
Patent number
US07273885B2

Reaction notes

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